Abstract
Rare-earth delafossites, ARCh2; A = alkali metal, R = rare-earth, Ch = chalcogen which consist of intercalated rare-earth metal dichalcogenides, host frustrated triangular lattices that are fertile ground for exotic phenomena. In most cases, the triangular rare-earth sublattice arises from R-3m (No. 166) structures with three layers of rare-earth metal dichalcogenide octahedra or P63/mmc (No. 194) structures with two such layers, analogous to those found in transition metal dichalcogenides. Substituting the alkali metal with Cu+ yields a distinct trigonal crystal symmetry─P-3m1 (No. 164)─in these structures. This symmetry change alters the coordination environment from ASe6 octahedra in R-3m AYbSe2 to CuSe4 tetrahedra in CuYbSe2, resulting in shortened rare-earth to rare-earth separations and significantly reduced interlayer distances. Using X-ray single-crystal diffraction, powder neutron diffraction, resistance, and specific heat measurements, a structural transition slightly below room temperature (258 K) is observed. The low-temperature structure is a lower-symmetry I2/m structure, accompanied by partial Cu-site vacancy ordering. The combination of Cu disorder and the triangular lattice geometry in CuYbSe2 provides a promising platform for investigating frustrated magnetism and unconventional transport phenomena.
| Original language | English |
|---|---|
| Pages (from-to) | 328-335 |
| Number of pages | 8 |
| Journal | Chemistry of Materials |
| Volume | 38 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 13 2026 |
Funding
The work at Michigan State University was supported by the U.S.DOE-BES under Contract DE-SC0023648. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The beam time was allocated to the SNAP instrument on proposal number IPTS-34311.1. XPS research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE. ORISE is managed by ORAU under contract number DESC0014664. All opinions expressed in this paper are the author’s and do not necessarily reflect the policies and views of DOE, ORAU, or ORISE.